#line 2 "library/template.hpp"
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

#include <bits/stdc++.h>
using namespace std;
// https://xn--kst.jp/blog/2019/08/29/cpp-comp/
// debug methods
// usage: debug(x,y);
#define CHOOSE(a) CHOOSE2 a
#define CHOOSE2(a0, a1, a2, a3, a4, x, ...) x
#define debug_1(x1) cout << #x1 << ": " << x1 << endl
#define debug_2(x1, x2)                                                        \
    cout << #x1 << ": " << x1 << ", " #x2 << ": " << x2 << endl
#define debug_3(x1, x2, x3)                                                    \
    cout << #x1 << ": " << x1 << ", " #x2 << ": " << x2 << ", " #x3 << ": "    \
         << x3 << endl
#define debug_4(x1, x2, x3, x4)                                                \
    cout << #x1 << ": " << x1 << ", " #x2 << ": " << x2 << ", " #x3 << ": "    \
         << x3 << ", " #x4 << ": " << x4 << endl
#define debug_5(x1, x2, x3, x4, x5)                                            \
    cout << #x1 << ": " << x1 << ", " #x2 << ": " << x2 << ", " #x3 << ": "    \
         << x3 << ", " #x4 << ": " << x4 << ", " #x5 << ": " << x5 << endl
#ifdef LOCAL
#define debug(...)                                                             \
    CHOOSE((__VA_ARGS__, debug_5, debug_4, debug_3, debug_2, debug_1, ~))      \
    (__VA_ARGS__)
#else
#define debug(...)
#endif

using ll = long long;
using vl = vector<ll>;
using Graph = vector<vector<ll>>;
using P = pair<ll, ll>;
#define all(v) v.begin(), v.end()
template <typename T> inline bool chmax(T &a, T b) {
    return ((a < b) ? (a = b, true) : (false));
}
template <typename T> inline bool chmin(T &a, T b) {
    return ((a > b) ? (a = b, true) : (false));
}
#define rep1(i, n) for(ll i = 1; i <= ((ll)n); ++i)
// https://trap.jp/post/1224/
template <class... T> constexpr auto min(T... a) {
    return min(initializer_list<common_type_t<T...>>{a...});
}
template <class... T> constexpr auto max(T... a) {
    return max(initializer_list<common_type_t<T...>>{a...});
}
template <class... T> void input(T &...a) {
    (cin >> ... >> a);
}
template <class T> void input(vector<T> &a) {
    for(T &x : a)
        cin >> x;
}
void print() {
    cout << '\n';
}
template <class T, class... Ts> void print(const T &a, const Ts &...b) {
    cout << a;
    (cout << ... << (cout << ' ', b));
    cout << '\n';
}
template <class T> void print(vector<T> x) {
    if(x.size()) {
        for(ll i = 0; i < x.size(); i++) {
            cout << x[i] << " \n"[i + 1 == x.size()];
        }
    }
}
#define INT(...)                                                               \
    int __VA_ARGS__;                                                           \
    input(__VA_ARGS__)
#define LL(...)                                                                \
    long long __VA_ARGS__;                                                     \
    input(__VA_ARGS__)
#define STR(...)                                                               \
    string __VA_ARGS__;                                                        \
    input(__VA_ARGS__)
#define REP1(a) for(int i = 0; i < a; i++)
#define REP2(i, a) for(int i = 0; i < a; i++)
#define REP3(i, a, b) for(int i = a; i < b; i++)
#define REP4(i, a, b, c) for(int i = a; i < b; i += c)
#define overload4(a, b, c, d, e, ...) e
#define rep(...) overload4(__VA_ARGS__, REP4, REP3, REP2, REP1)(__VA_ARGS__)

ll inf = 3e18;
vl dx = {1, -1, 0, 0};
vl dy = {0, 0, 1, -1};
#line 2 "yukicoder/515/a.cpp"
#include <atcoder/fenwicktree>
using namespace atcoder;
// #include <atcoder/segtree>
#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;

void solve() {
    LL(q, y);
    vector<string> s(q);
    input(s);
    cpp_int ok = ll(1e15), ng = -1;
    auto cul = [&](cpp_int x) {
        vector<cpp_int> a;
        for(auto st : s) {
            if(st == "min") {
                cpp_int i = a.back();
                a.pop_back();
                cpp_int j = a.back();
                a.pop_back();
                a.push_back(min(i, j));
            } else if(st == "max") {
                cpp_int i = a.back();
                a.pop_back();
                cpp_int j = a.back();
                a.pop_back();
                a.push_back(max(i, j));
            } else if(st == "+") {
                cpp_int i = a.back();
                a.pop_back();
                cpp_int j = a.back();
                a.pop_back();
                a.push_back(i + j);
            } else if(st == "X") {
                a.push_back(x);
            } else {
                debug(st, stoll(st), cpp_int(stoll(st)));
                a.push_back(stoll(st));
                debug("ok");
            }
        }
        return a[0];
    };
    while(ok > ng + 1) {
        auto mid = (ok + ng) / 2;
        if(cul(mid) >= y)
            ok = mid;
        else
            ng = mid;
    }
    if(cul(ok) == y) {
        print(ok);
    } else
        print(-1);
}
int main() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    cout << std::setprecision(16);
    int t = 1;
    rep(_, t) {
        solve();
    }
}